Tutorial II: Fine-grained power delivery and management in SoCs: Advances in control and circuit design

Abstract

Fine grained spatiotemporal power management in SoCs require DC-DC converters and embedded voltage regulators that are compact, energy-efficient, and able to operate over a large dynamic range. Buck converters, switched capacitor converters and linear regulators have become key IP blocks to delivery power in diverse load circuits. In the first part of the talk, we will introduce the key design concepts and advances in these three converter/regulator topologies. Then we will focus on linear regulators as key enablers for dynamic voltage and frequency scaling (DVFS) in ultralow power SoCs. Linear regulators, including low-drop out regulators are the popular choice for on-die voltage regulation. Linear regulators have been traditionally designed for supply sensitive analog circuits which typically represent DC loads with small current transients and operate over a narrow operating range. However, an increasing number of power domains, decreasing decoupling capacitance per domain, large current transients and an ever expanding current/voltage dynamic range in digital circuits motivate the investigation of alternative topologies for linear regulators, including all-digital and hybrid analog/digital loops. In this talk we will present some of the recent work on linear regulators suitable for digital load circuits. We will describe models and Silicon measurements of all-digital and hybrid regulators that provide wide operating ranges and high current efficiencies across the entire range. This requires innovation in both linear and non-linear control topologies and their circuit implementations that can address key challenges in power management. We will introduce switched mode control, discrete time and continuous time systems as well as our recent work on unification of clocking and regulation for resilience to large dynamic variations.